1. Field of the Invention
This invention relates to a fire-resistant sandwich core assembly, particularly for use in fire doors.
2. Description of the Prior Art
Fire doors are employed in buildings to prevent fire propagation along corridors in the event of a fire. Fixed structures, such as the internal walls of the building, can more easily be made fire-resistant by using gypsum-based materials. A fire door however presents a problem. In the prior art, the interior of the door was filled with a mixture of perlite and gypsum to give the door the necessary fire-resistant properties. This made the door heavy and very difficult to attach to the hinges. If enough wood was provided around the periphery of the door to allow attachment to the hinges, the performance of the door would deteriorate to the point where it would not withstand a fire for the required amount of time to meet generally accepted test criteria. Also, a door having a core of gypsum and perlite is difficult to mass-produce. The perlite-gypsum mixture has to be poured into a mold, allowed to set, and then removed and fitted into an appropriate frame. Another problem with such doors has been the tendency to delaminate as a result of constant opening and closing.